1. Field of Invention:
This invention relates generally to thermotherapy, and in particular to a non-invasive technique for relieving pain and obtaining other salutary effects in which the skin surface of a patient overlying a problem region is subjected to a corona discharge beam derived by periodic bursts of radio frequency energy whose repetition rate is at a sonic frequency.
2. Status of Prior Art:
The term "problem region" as used herein refers to a set of muscles, an arthritic joint or any other site underlying the skin of a patient which is causing difficulty and which lends itself to treatment by thermotherapy.
The interior of the human body has a normal temperature level which is usually said to be 98.6.degree. F. But actually, in the course of each 24-hour period, the body temperature rises above or falls somewhat below this nominal value. Body temperature is determined by the relationship existing between the amount of heat internally generated, which depends on basal metabolism and the amount of heat escaping from the body. Additional heat is produced as a result of muscular activity, this being dissipated by an increase in radiation, conduction or evaporation from the skin surface and by more rapid and deep breathing. If the heat produced by the body surpasses heat losses therefrom, this gives rise to fever.
Medical practitioners since ancient times have known that the application of heat to the body is useful in the relief of muscle soreness and various aches and pains, as well as in the treatment of certain pathological conditions. Thus the use of heat for the treatment of arthritis and other abnormalities is now commonplace. Hot water bottles and electrical heating pads are in widespread use, not merely to provide warmth, but also to afford a degree of relief or therapy for various conditions. In applying heat to the surface of the body, one may do so by convection, by direct contact with a warmed substance; that is, by conduction, or by radiating energy into the body.
As pointed out in chapter 10, "Therapeutic Heat" in the text Therapeutic Heat and Cold, edited by Justus F. Lehmann and published in 1982 by Williams and Wilkins, it is generally accepted that heat produces desirable therapeutic effects, for it increases the extensibility of collagen tissues, it decreases joint stiffness, and it affords pain relief. Moreover, heat relieves muscular spasms, it aids in the resolution of inflammatory infiltrates, edema and exudates, and it enhances blood flow.
The exact physiological mechanisms by which applied heat creates soothing and analgesic effects are not known. However, regardless of how heat is generated, the result within the heated tissue is essentially the same, for heat produces a rise in the temperature of the tissue with a concomitant increase in metabolism. As a consequence, there is a relative increase in the accumulation of metabolic wastes such as carbon dioxide and acid metabolites. And because heat acts as a vasodilator, this dilation results in increased local circulation and leads to improved cellular nutrition and to an enhanced exchange of wastes. Further benefits are obtained because a greater number of phagocytes and antibodies are carried by the blood into the region being heated.
A technique in accordance with the invention makes use of conversive heating which involves the transformation of some other form of energy into heat. The most commonly used sources of such energy are radio waves in the short wave and microwave bands of the electromagnetic wave spectrum, and ultrasonic energy. Shortwave diathermy uses radio waves in the 10 to 100 MHz frequency range, the human tissues being treated with high-frequency current, either by way of induction or conduction. In microwave diathermy, the frequency is usually about 2500 MHz. While shortwave diathermy tends to spread widely in the body tissues, microwaves are quasi-optical and can be focused and directed for the heating of small selective areas.
Ultrasonic therapy employs high-frequency sound waves, but this energy is selective in its heating properties. Because ultrasonic energy is reflective at interfaces in the body, in excessive dosages it may be destructive.
The present invention involves a therapeutic technique in which a corona discharge beam is created by applying to a discharge electrode bursts of radio-frequency energy whose repetition rate is at a sonic frequency. Hence of background interest are the Di Mino Pat. Nos. 3,676,633 and 3,617,684, in which a corona discharge beam is applied to a resistor in a printed circuit so as to change the ohmic value thereof. These patents, however, have nothing to do with thermotherapy.
Also of background interest is the Hance et al. U.S. Pat. No. 4,368,410, which discloses an ultrasound therapy technique in which the ultrasound energy is pulsed. In the Kuris et al. U.S. Pat. No. 3,980,906, ultrasonic energy modulated at a sonic rate is applied to a vibrating toothbrush or razor. And in Indeck, U.S. Pat. No. 4,343,301, non-invasive neurosurgery is performed using two ultrasonic beams to create a low frequency beat pattern.
Also in the field of ultrasonic therapy, we find the U.S. Pat. Nos. to Kofsky et al., 4,177,819; Nemic, 4,153,061; and Griffith, Jr., 3,096,768.